1. Field of Invention
This invention relates to missile guidance systems and methods. Specifically, the present invention relates to systems and methods for guiding hypersonic projectiles.
2. Description of the Related Art
The U.S. Army has shown that a tungsten long-rod penetrator delivering in excess of 10 megajoules of energy at hypersonic velocity to the armor of a tank can penetrate the armor and destroy the tank. This has involved boosting the rod to hypersonic speed using a rocket. For guidance, hypervelocity anti-tank weapon prior art has focused on the use of laser beam-rider guidance technology. Unfortunately, the rocket has heretofore left a large exhaust plume which has been impenetrable by optical, laser or infrared (IR) band energy to provide guidance commands from the launch platform. Thus the target is obscured when guidance is required.
Millimeter wave radar can penetrate the plume but usually does not offer sufficient resolution to provide the degree of guidance accuracy required.
Weapon system designers have consequently been forced to go to extraordinary means to deal with these difficulties, including commanding offset flight trajectories. These design concessions result in increased system complexity, compromised performance, and higher cost.
Thus, a need remains in the art for a weapon system that avoids the optical, laser, and IR transmissivity problems associated with a large rocket motor exhaust plume, allowing optimized performance and a greatly simplified weapon system at lower cost.
The need in the art is addressed by the hypervelocity projectile guidance system of the present invention. The inventive system includes a first subsystem for determining a target location and providing data with respect thereto. A second subsystem calculates trajectory to the target based on the data. The projectile is then launched and guided in flight along the trajectory to the target.
In the illustrative application, the projectile is a tungsten rod and the first subsystem includes a forward-looking infrared (FLIR) imaging system and a laser range finder. The second subsystem includes a fire control system. The fire control system predicts target location and may include an optional inertial measurement unit. The projectile is mounted in a missile launched from a platform such as a launch vehicle. The missile is implemented with a guidance system and a propulsion system. After an initial burn, the missile launches the projectile while in flight.
In accordance with the present teachings, the guidance system includes a transceiver system mounted on the projectile. The transceiver system includes a low-power, continuous-wave, millimeter wavelength wave emitter. A system is included at the launch platform for communicating with the projectile. The platform system sends a blinking command to the projectile and measures the round trip delay thereof to ascertain the range of the projectile. Velocity is determined by conventional Doppler techniques or differentiation. Azimuth and elevation are then determined by a monopulse antenna on the launch platform. As a consequence, the platform ascertains the location of the projectile and the impact point thereof. The platform generates a command to the projectile which is received by the projectile and used to actuate aerodynamic control surfaces or radial impulse motors ahead or behind the center of gravity to adjust the trajectory and impact point thereof as necessary.